1. Field of the Invention
The present invention relates to a copier, laser printer, facsimile apparatus or similar image forming apparatus.
2. Description of the Background Art
Japanese Patent Laid-Open Publication No. 5-27623, for example, discloses an image forming apparatus including a fixing device generally made up of a heat roller, a fixing roller, an endless belt passed over the heat roller and fixing roller, a press roller pressed against the fixing roller with the intermediary of the belt, and a tension roller for applying tension to the belt. A paper sheet or similar recording medium carrying a toner image thereon is conveyed via a nip between the press roller and the belt, so that the toner image is fixed on the paper sheet. The heat roller or the press roller accommodates a halogen lamp or similar heater. A coating roller coats silicone oil on the belt in order to promote parting of the paper sheet from the belt after fixation.
In the image forming apparatus of the typed described, all the structural elements including the belt, heat roller, fixing roller, press roller, tension roller and coating roller are mounted on an apparatus body integrally with each other. This, coupled with the heater disposed in the heat roller or the press roller, increases the number of parts to assemble and complicates the structure. Further, the structural elements are difficult to handle because they are apt to break when the belt is inserted into the apparatus body or at the time of maintenance. Moreover, when the belt is replaced, the oil smears the operator""s hand. The conventional apparatus is therefore not desirable from the production, assembly and maintenance standpoint.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Laid-Open publication No. 2000-66541.
It is therefore an object of the present invention to provide an image forming apparatus that promotes easy, efficient mounting of a fixing device to an apparatus body and facilitates the maintenance of the fixing device.
An image forming apparatus of the present invention includes an apparatus body, a heat roller, a fixing roller, a press roller pressed against the fixing roller, an endless belt passed over the heat roller and fixing roller, and a tension roller applying tension to the endless belt. The heat roller, fixing roller, endless belt and tension roller are constructed into a unit member, which is removably mounted to the apparatus body.